signal handler

Debian Linux project released the OpenSSH security updates for computers powered by its Debian Linux operating systems. The Openssh package has remote unsafe signal handler DoS Vulnerability. It has been discovered that the signal handler implementing the login timeout in Debian’s version of the OpenSSH server uses functions which are not async-signal-safe, leading to a denial of service vulnerability.

Systems affected by this issue suffer from lots of zombie sshd processes. Processes stuck with a “[net]” process title have also been observed. Over time, a sufficient number of processes may accumulate such that further login attempts are impossible. Presence of these processes does not indicate active exploitation of this vulnerability.